The feel force is controlled by the feel computer, and is exerted by the feel actuator acting through the feel unit.
In each of the two groups of components in the computer, a Qc-sensing(pitot) bellows acts through a leaf spring upon a pivot linkage to displace a force balanced slide valve. A cam, connected by linkage to the horizontal stabilizer, acts through another leaf spring in opposition to the Qc-sensing bellows.
The sum of these two forces, together with hydraulic return pressure, loads the force balance valve to pressurize the associated chamber of the feel actuator. The force balance valve closes when the force exerted by feel pressure on the opposite end of the valve balances the input forces. The feel pressure acts on the feel actuator rams to apply a force which resists rotation of the feel unit cam.
As the cam is connected to the aft quadrant, this resistance plus feel unit centering spring tension resists control column displacement from neutral.
[This message has been edited by CCA (edited 18 September 2000).]